You are not really listening to me, what I said was... For older adults, exchanges of this sort are all too familiar. Is the problem one that primarily reflects age-related impairments in sensory abilities or, instead, is it more cognitive in nature, reflecting a failure to carefully listen? Accurate speech perception requires listeners to evaluate a number of different sources of information about the content of spoken communications, including the speech signal and semantic context. In some instances, these different sources of information converge on the same perception, whereas in others they can lead to dramatically different perceptual responses. For example, an individual speaking to a nurse at a physician's office who is relying primarily on context-driven information might misperceive the sentence The Doctor said to remind you to take the BILL as The Doctor said to remind you to take the PILL. In our initial work in this area (Rogers, Jacoby, and Sommers, 2012), we have coined the term false hearing to refer to perceptual errors in which individuals rely more on context-driven than sensory-driven information, yet are nevertheless highly confident that they actually heard the stimulus. The proposed research will investigate how older and younger adults weigh sensory information and semantic context during online speech perception. In addition, we will establish the extent to which errors such as the Bill-Pill mistake reflect metacognitive failures that also produce analogous errors in other perceptual and cognitive domains. The application is highly innovative in that it integrates principles of cognition, metacognition and audiology to examine how age-related reductions in cognitive control may impair older adults' ability to flexibly vary their bases of responding. Specifically, we propose that, under conditions of equivalent intelligibility, older adults will weigh semantic context more heavily than the sensory signal as a basis for responding and will be less flexible than young listeners in switching to sensory- based responding when dictated by the prevailing circumstances. Three specific aims will be addressed in the application. Specific Aim 1 will establish how age-related changes in metacognitive abilities affect listeners' awareness of their speech perception difficulties using more naturalistic (sentence) stimuli than has been used previously. Specific aim 2 will examine how individual and age differences in cognitive control might alter communicative behaviors, such as requesting repetitions and careful listening, that could substantially improve speech perception in older adults. Specific Aim 3 will assess correlations between measures of false hearing, false seeing and false remembering to establish the extent to which these types of errors may be attributable to a common mechanism, such as cognitive control. Taken together, the findings will provide the first studies of how metacognitive abilities operate during online speech perception and whether age-related declines in metacognition contribute to the poorer speech perception performance of older adults.